1. Field of the Invention:
This invention relates generally to extensible and retractable members, and, specifically, to such members and a method of forming the same for use as rigid supports, as in the case of aerial mast and antennae.
2. Description of the Prior Art:
Many types of extensible and collapsible members are known, such as antennae used in communication, support platforms used in harvesting fruit, booms used in inspecting and servicing machinery, elevators for fire hoses, and the like.
The typical prior art device utilized a telescoping action which resulted in several inherent problems. These problems included the length of span and span strength, the support or reinforcement provided by a adjacent spans, and the number of spans needed to effect a desired amount of extension.
U.S. Pat. No. 4,625,475, "Extensible Mast" to Henry J. McGinnis, issued Dec. 2, 1986, showed an improved extensible mast which utilized a plurality of tape reels mounted on a portable base. Guide rollers on the base received the respective longitudinal edges of tape dispensed from the tape reels and oriented the tape whereby the tapes were fed upwardly by a drive mechanism in planes parallel to a central, vertical axis to form a rigid structure. A geared winding mechanism, including a plurality of rotatable windings, was located above the drive mechanism and wrapped a wrap material about the rigid structure to reinforce the structure as it was being erected.
The apparatus shown in U.S. Pat. No. 4,625,475 provided an extensible and collapsible mast which was strong and rigid when extended and which was free from problems associated with the telescoping action. The present invention in directed to further improvements in such an extendible mast, particularly with regard to an improved drive means for erecting and collapsing the rigid structure which is erected by orienting and successively uniting similar flexible strips of material which can be retracted by successively disassembling the same strips.
The device of the invention features a geared winding mechanism located beneath the drive mechanism and above the guide rollers whereby the flexible strips are wound after being oriented and united but prior to encountering the improved drive mechanism.
The combined features of the present invention provide an extensible mast or antenna which is erectable from a portable base and which has a very small volume or bulk when retracted for ease of transportation. The improved mast or antennae is strong and rigid and free from the problems associated with the prior art devices.